Freeze-drying and irradiation effects on stability of the porcine peritoneum in vitro

BACKGROUND: Collagen membrane following super(60)Co g ray germicidal treatment can promote the crosslinking of collagen molecule and affect its stability. OBJECTIVE: To determine the in vitro stability of freeze-dried and irradiated porcine peritoneum by assessing enzymolysis time of collagenase in porcine peritoneum following irradiated and freeze-dried treatment. DESIGN, TIME AND SETTING: This animal experiment was performed at the Burn Institute, Nanchang University, Association Mechanics Laboratory, Nanchang University-New Sans Company, Chinese Crude Drug Solid Preparation Nation Project Research Center of Jiangxi Traditional Chinese Medical College and Jiangxi Tianzhao Technology Development Company from July 2007 to June 2008. MATERIALS: Six healthy living pigs were used to sterilely obtain fresh porcine peritoneum. super(60)Co g ray irradiation equipment was purchased from Jiangxi Tianzhao Technology Development Company. METHODS: Fresh porcine peritoneum was assigned into 4 groups. In the fresh group, fresh porcine peritoneum was washed in saline containing 1x10 super(5) U/L gentamicin, trimmed, and then immersed in protective solution for 15 minutes. Finally, samples were placed in 0-4 C for use. In the freeze-dried group, fresh porcine peritoneum was placed in EMDE+10% glycerol for 15 minutes, placed in -78 C to form ice crystal, froze and dried in a vacuum freeze-drying machine for 6 hours, and then took out at room temperature for use. In the irradiation group, on the basis of freeze-dried group, the porcine peritoneum was irradiated with 25 kGy super(60)Co g ray in an irradiation equipment for 72 hours, and then maintained in 0-4 C for use. In the freeze-dried + irradiation group, on the basis of irradiation group, the porcine peritoneum was irradiated with 25 kGy super(60)Co g ray in an irradiation equipment for 72 hours, and then maintained at room temperature for use. MAIN OUTCOME MEASURES: 5-mm wafer of each group porcine peritoneum were dealt with type I collagenase, and digested time was recorded. RESULTS: Collagenase enzymolysis time of the porcine peritoneum was respectively (9.6c1.2), (6.1c1.6), (29.2c3.), (23.5c2.6) minutes in four groups. Enzymolysis time was significantly longer in the irradiation group and the freeze-dried + irradiation group compared with the fresh group and the freeze-dried group (P < 0.05). However, no significant differences in enzymolysis time of the porcine peritoneum were detected between the fresh group and